This invention relates to temperature indicating means and more particularly to a band or strip of temperature sensitive material which can be mounted or secured to a fire fighter's uniform for providing an indication to the user of the temperature of the environment in which he is operating.
As one knows, each year many lives are lost due to fire including the lives of fire fighters who oftentimes are severely injured based on the tremendous flucuations in temperature which can occur during a typical fire.
In view of such circumstances, fire fighters wear protective clothing which function to isolate the body of the fire fighter from the excessive temperatures. In any event, it is known that temperatures beyond certain limitations can result in serious damage to both the fire fighter's uniform as well as his person.
Based on prior art technology, there is no reasonable or convenient way of providing a temperature indication to a fire fighter, and if such a person exposes himself for a prolonged period to excessive temperatures, serious injuries may result. According to studies, it has been determined that the fire fighter is in danger with conventional fire fighting uniforms when he is exposed to temperatures in excess of 300 degrees F. At a temperature of 300 degrees F., the fire fighter can operate in such an environment for a relatively short period, and if continued exposure occurs, he would be in danger.
Temperatures above 300 degrees F. as 400 degrees F. present even greater problems and place the fire fighter in greater danger. When temperatures approach 500 degrees F. or greater, this is a definite danger zone and no person or equipment should be exposed to such temperatures for any length of time. Thus in operating with temperatures close to 500 degrees F., the fire fighter's outfit will shrink and injury becomes unavoidable. In view of such circumstances, it has been determined that a temperature indicating means to be secured to the fire fighters uniform which will inform the fire fighter of the operating temperature would be extremely beneficial in saving lives and assuring the overall safety of the fire fighter.
The prior art is replete with numerous devices for indicating temperature apart from the conventional thermometer. For example, LCD devices have been extensively employed in the prior art as temperature indicating devices and have been used to monitor body temperature and other temperatures as well.
See for example, U.S. Pat. No. 4,140,016 entitled NOVEL COMPOSITIONS, DEVICES AND METHOD issued Feb. 20, 1979 to J. L. Ferguson. This patent shows a temperature sensing device which employs an inert compound in mixture with nematic type liquid crystal compounds. Liquid crystal compounds exhibit color changes with temperature to enable one to provide an indication of the temperature by a changing color.
Other patents as U.S. Pat. No. 4,220,680 entitled MULTILAYERED STRUCTURE INCORPORATING A THERMOMETER issued on Sept. 2, 1980 to P. E. Corsi. This patent shows a multiple layered structure of plastic material including a liquid crystal temperature indicator to provide a strip for indicating temperature. The liquid crystals change color as the temperature varies. In any event, there are other patents which show various devices which can be used to monitor temperature and which employ liquid crystal devices. See for example, U.S. Pat. Nos. 3,999,838, 3,114,836, 3,951,133, and 3,802,945.
Essentially, most of the above noted patents employ liquid crystal devices which may be mixed with various other substances to provide a temperature indication by the color change accommodated by liquid crystals when subjected to varying temperatures. As one can ascertain, such devices present problems in that in order to inform a fire fighter of a dangerous temperature condition, he has to visualize a color accurately, and therefore he may not be able to inform himself of the temperature by utilizing prior art liquid crystal techniques.
As one can ascertain, based on the nature of the fire and operation of a fire fighter in battling a blaze, such liquid crystal devices may present great problems in that color change cannot be readily perceived. The devices are basically reflective devices which may confuse a fire fighter as to the temperature of the environment.
It is, therefore, an object of the present invention to provide a temperature indicating means which is extremely reliable in operation, which provides an accurate means of indicating a temperature range and which is capable of being conveniently secured to the uniform of a fire fighter. The apparatus to be described is simple to manufacture while providing a positive indication of the temperature environment in which fire fighter is operating.